In automobile mounted fuel tank systems, in consideration of the fact that engine running times are becoming shorter, for example, in hybrid vehicles, and in order to improve fuel efficiency it is desirable for canisters to be capable of being purged without having to rely on negative pressure from the engine. In Japanese Patent Application Laid-Open No. 2003-314381, a fuel vapor recovery apparatus is described that sucks vapor from a canister with a suction pump, liquefies the fuel vapor in a liquefier, and returns it to the fuel tank.
However, in the structure of JP-A No. 2003-314381, cooling energy is required in order to cool and liquefy the fuel vapor in the liquefier, and further improvements to energy efficiency are required.